Formation of ortho-alkylated aromatic amines from N-alkylated aromatic amines

Abstract

This invention relates to a process for producing ring alkylated aromatic amines where the alkyl substituent is ortho to the amino group by reacting an N-alkylated aromatic amine with a C 2-10 olefin in the presence of a solid phase acidic catalyst, e.g., silica-alumina or a zeolite. High conversion and selectivity is achieved by maintaining a mole ratio of olefin to amine of from about 1-10:1 and an operating pressure of at least 50 psig.

What is claimed is: 
     
       1. In a process for forming ring alkylated aromatic amines by reacting an olefin with an aromatic amine in the presence of an acidic catalyst, the improvement for enhancing the conversion of a C 2-4  N-alkylated aniline to a ring alkylated aniline where the ratio of ortho-alkylated aniline to para-alkylated aniline product is greater than about 3 to 1 and the conversion of aromatic amine to ring alkylated aniline is greater than about 20% which comprises: contacting a C 2-4  olefin with an aromatic feed containing N-alkylated aniline of the structure ##STR6## where, R 1  is C 2-4  alkyl and R 2  is hydrogen or C 2-4  alkyl;   maintaining an olefin to amine molar ratio of about 10-1:1;   maintaining a pressure of at least 50 psig in the reaction zone; and   utilizing a solid phase, acidic catalyst.   
     
     
       2. The process of claim 1 wherein the pressure in said reaction is at least 200 psig. 
     
     
       3. The process of claim 2 wherein reaction temperature is maintained sufficiently low within a temperature range of from 50° to 425° C. and wherein the space velocity is maintained sufficiently high at such temperature such that a significant amount of ortho-alkylated product produced in the reaction zone is not rearranged to the para isomer. 
     
     
       4. The process of claim 3 wherein the liquid hourly space velocity of the feed containing N-alkylated aniline to the reactor is from 0.05 to 4.0 hours -1 . 
     
     
       5. The process of claim 4 wherein the pressure in the reaction zone is maintained at level from about 200 to 2000 psig. 
     
     
       6. The process of claim 5 wherein the temperature utilized for converting N-alkylated aniline is from 200° to 425° C. when the olefin is ethylene, 100° to 375° C. when the olefin is propylene and the temperature is from 50° to 250° C. when the olefin is isobutylene. 
     
     
       7. The process of claim 6 wherein the solid phase, acidic catalyst is a hydrogen or rare earth exchanged zeolite and X is O. 
     
     
       8. The process of claim 6 wherein the catalyst is a silica-alumina having from about 5 to 25 percent alumina. 
     
     
       9. The process of claim 6 wherein said catalyst is gamma-alumina. 
     
     
       10. The process of claim 4 wherein said olefin is propylene. 
     
     
       11. A process for forming an isopropyl aniline where the isopropyl group is ortho to the amine which comprises reacting a feed containing an N-isopropyl aniline with propylene in the presence of gamma alumina, silica-alumina, or zeolite at a temperature from 100° to 375° C., a pressure from 200 to 2000 psig and a mole ratio of propylene to N-isopropyl aniline of from 10:1 to 1:1, and a space velocity of 0.05 to 4.0 hours -1 . 
     
     
       12. A process for preparing a ring alkylated product from an N-alkylated aniline wherein the ortho to para isomer ratio exceeds 6:1 and a conversion level greater than 30% by weight of incoming N-alkylated reactant which comprises contacting an aromatic amine feed containing at least 25 mole percent of an N-alkylated reactant of the formula   where, R 1  is C 2-4  alkyl, and R 2  is hydrogen or C 2-4  alkyl with a C 2-4  olefin in the presence of gamma-alumina or an acidic zeolite catalyst, maintaining a temperature from 150° to 350° C., maintaining a mole ratio of olefin to N-alkylated reactant of from 2-10:1, and maintaining a pressure from 500 to 1000 psig and an LHSV of from 0.1 to 1 hr -1 .   
     
     
       13. The process of claim 12 wherein said olefin is propylene, said aromatic feed contains from 0 to 0.5 moles aniline and 0.5 to 1 mole of N-isopropyl aniline per mole of aromatic feed, said catalyst is a hydrogen or rare earth exchanged Y zeolite, the contacting is carried out a pressure from about 200 to about 2000 psig and the temperature is from 225°-275° C. and X is O. 
     
     
       14. The process of claim 13 wherein the ring alkylated product is withdrawn from the reactor when the rate of formation of the ortho-alkylated product is slower than rate of decomposition of said ortho-alkylated product.